1. Field of the Invention
The present invention relates to a personal watercraft. More particularly, the present invention relates to a construction of a fuel supply passage configured to supply a fuel to an engine of the personal watercraft.
2. Description of the Related Art
In recent years, jet-propulsion personal watercraft have been widely used in leisure, sport, rescue activities, and the like. A typical personal watercraft includes an engine mounted substantially at a center position in a longitudinal direction within a body surrounded by a hull and a deck. The personal watercraft is equipped with a water jet pump behind the engine and a fuel tank forward of the engine. The engine drives the water jet pump, which pressurizes and accelerates water sucked from a water intake generally provided on a bottom surface of the hull and ejects it rearward from an outlet port. Thereby, the personal watercraft is propelled.
The engine mounted in the personal watercraft typically includes multiple cylinders that are arranged along the longitudinal direction of the watercraft (e.g., in-line multi-cylinder engine, and a V-type multi-cylinder engine). The engine is provided with fuel injectors such as electronically controlled fuel injectors respectively provided for the cylinders to inject a predetermined amount of fuel into air-intake passages or into a combustion chamber. The fuel tank has an outlet from which a fuel outflows and a return port through which some of the fuel is returned. The fuel stored within the fuel tank is delivered from the outlet to a fuel distribution pipe. The fuel distribution pipe extends along the longitudinal direction of the watercraft, and the fuel injectors are connected to a side portion of the fuel distribution pipe. Therefore, some of the fuel flowing within the fuel distribution pipe is distributed to the fuel injectors and the remaining fuel is returned to the fuel tank through the return port.
As described above, the fuel tank is placed forward of the engine. The outlet of the fuel tank is typically connected to a front portion of the fuel distribution pipe which is close to the outlet, and the return port is connected to a rear portion of the fuel distribution pipe. Therefore, the fuel outflowing from the fuel tank flows from the front portion (upstream portion) to the rear portion (downstream portion) within the fuel distribution pipe, and is distributed to the fuel injectors at positions of the fuel distribution pipe.
The engine tends to heat up to a high temperature during operation, and it takes some time for the engine to sufficiently decrease the temperature after the engine stops. Therefore, after the engine stops, some of the fuel remaining within the fuel distribution pipe is vaporized. Since the personal watercraft is constructed such that its center of gravity is located slightly rearward of the center position in the longitudinal direction, a fore part of the body is located higher than an aft part of the body when the watercraft is at rest on the water without a rider. When the rider rides on the watercraft and starts up the engine, the fore part is located higher than the fore part of the watercraft without the rider. In this construction, the vaporized fuel within the fuel distribution pipe tends to remain within the front portion of the fuel distribution pipe (on the upstream portion in a flow passage of the fuel) due to a buoyant force, when the watercraft is at rest on the water and the engine is starting up.
However, the vaporized fuel remaining within the front portion of the fuel distribution pipe while the watercraft is at rest on the water is guided from the front portion to the rear portion within the fuel distribution pipe, together with a liquefied fuel (hereinafter referred to as liquid fuel), when the engine starts up next. As a result, the vaporized fuel is mixed with the liquid fuel being distributed from the fuel distribution pipe to the fuel injectors. Under this condition, the fuel injectors cannot inject the liquid fuel in appropriate amount, thereby making it difficult for the engine to operate stably during start-up.